12-15 Paul turns his attention to the kind of materials Christian workers are using: the materials of preaching the cross for salvation, building up believers (cf. 1:18), and living a Christian life that is commensurate with that preaching (2:2-4).

• The purity and depth of such Christian teaching and a life corresponding to it are crucial,

• Because that kind of building material will stand the test of fire on the day of the Lord's judgment.

Since valuable metals and precious stones were used to adorn ancient temples Rev 21:18-21

• Paul could have taken his imagery from Herod's temple in Jerusalem

• Or from the beautiful public and religious buildings in Athens and Corinth.

• Such imagery would be sufficient to convey the thought of pure doctrine.

• The frames of ordinary houses and buildings were built of wood; hay or dried-grass, mixed with mud, was used for the walls; and roofs were thatched with straw or stalks.

• So the kind of dull teaching and life that’s represented by these lesser things